Very early implementation for HTMLMediaElement / Web Audio API integration

media/filters/audio_renderer_sink.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_
+#define MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace media {
+
+// AudioRendererSink is an abstract base class representing the end-point for
+// rendered audio in the renderer process.  An implementation is expected to
+// periodically call Render() on a callback object.  A typical implementation
+// will talk with the browser process to get a rendered audio stream to the
+// audio hardware.
+
+class AudioRendererSink
+    : public base::RefCountedThreadSafe<media::AudioRendererSink> {
+ public:
+  class RenderCallback {
+   public:
+    virtual void Render(const std::vector<float*>& audio_data,
+                        size_t number_of_frames,
+                        size_t audio_delay_milliseconds) = 0;
+
+    virtual void SetAudioRendererSink(media::AudioRendererSink* audio_sink) { }
+
+   protected:
+    virtual ~RenderCallback() { }
+  };
+
+  // Starts audio playback. Returns |true| on success.
+  virtual bool Start() = 0;
+
+    // Stops audio playback. Returns |true| on success.
+  virtual bool Stop() = 0;
+
+  // Sets the playback volume, with range [0.0, 1.0] inclusive.
+  // Returns |true| on success.
+  virtual bool SetVolume(double volume) = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_